1. Field of the Invention
The present invention relates to an apparatus and method for applying surgical staples to body tissue. More particularly, this invention relates to a laparoscopic or endoscopic surgical stapling apparatus which is at least partially powered by a low pressure pneumatic system.
2. Background of the Invention
In laparoscopic procedures, surgery is performed in the interior of the abdomen through a small incision. In endoscopic procedures, surgery is performed in any hollow viscus of the body through narrow endoscopic tubes inserted through small entrance wounds in the skin. Laparoscopic and endoscopic procedures generally require that any instrumentation inserted into the body be sealed, i.e., provisions must be made to ensure that gases do not enter or exit the body through the laparoscopic or endoscopic incision as, for example, in surgical procedures in which the surgical region is insufflated. Moreover, laparoscopic and endoscopic procedures often require the surgeon to act on organs, tissues and vessels far removed from the incision, thereby requiring that any instruments being used in such procedures be long and narrow while being functionally controllable from one end of the instrument, i.e. the proximal end.
Examples of surgical instruments having laparoscopic and/or endoscopic application are disclosed in commonly assigned U.S. Pat. No. 5,040,715 to Green et al., U.S. Pat. No. 5,071,430 to de Salis et al., U.S. Pat. No. 5,084,057 to Green et al. and U.S. Pat. No. 5,100,420 to Green et al. The instrument disclosed in the '715 patent to Green et al. is adapted to place one or more rows of staples endoscopically to perform gastrointestinal anastomosis. The instrument disclosed in the '430 patent to de Salis et al. endoscopically drives fasteners into body tissue for ablation of organs. The instruments disclosed in the '057 and '420 patents to Green et al. are adapted to surgically apply clips to body tissue in endoscopic procedures.
While the above developments represent major advances in endoscopic and laparoscopic instrumentation, the present invention is directed to further improvements whereby the handle section incorporates a pneumatic system to alleviate the degree of manually applied force required to actuate the instrument.
Surgical instruments having handle mechanisms which incorporate pneumatic systems or self contained powered units are described in U.S. Pat. Nos. 3,618,842, 3,643,851, 3,662,939, 3,717,294, 3,815,476 and 3,837,555. Typically, the pneumatic system in these instruments include a replaceable cylinder which supplies gas (e.g., carbon dioxide or nitrogen) at relatively high pressure (e.g., 800 psig.) to power the instrument. The high pressure gas used in these instruments requires the instruments to be of relatively heavy construction in order to solely accommodate the high pressure involved. Consequently, these design requirements preclude the incorporation of such high pressure gas units in endoscopic instrumentation which typically is more delicate in construction and is not capable of withstanding the high pressure delivered by these units.
Therefore, there is a need for a pneumatic system or self-powered gas unit of relatively low pressure that can be incorporated in an actuating or handle mechanism of an endoscopic or laparoscopic instrument, and which is capable of generating the substantial forces required to operate the instrument. Also, although it may be desirable to perform most of the functions of the endoscopic apparatus using the self-powering elements in the apparatus, it may also be desirable for the initial function to be at least partly manual. For example, if the initial function is to advance the staple for pre-positioning, it is preferably initiated manually so that it can be performed slowly and precisely and the results inspected and corrected if necessary before the automatic self-powered portion of the operating sequence begins. See, for example, U.S. Pat. Nos. 4,349,028 and 4,331,277 to Green.
One embodiment of the present invention contemplates an endoscopic apparatus adapted to endoscopically apply staples to attach a surgical mesh to body tissue to reinforce a surgical repair of the body tissue, as in hernia repair.
In hernia surgery a suitable mesh material is generally sutured over the opening in the tissue. The mesh material is often also attached by sutures and left within the opening to act as a reinforcing agent for tissue regrowth in the area of the surgery. One example of a mesh material currently utilized in hernia surgery includes a polypropylene material marketed by the Ethicon Division of Johnson & Johnson, New Brunswick, N.J., under the trademark MARLEX. Another example of a mesh material is a tri-fluoroethylene material marketed by W. L. Gore & Associates, Newark, Del., under the tradename GORE-TEX. Another example is a polypropylene mesh marketed by the assignee under the trademark SURGIPRO.TM..
U.S. Pat. No. 4,944,443 to Oddsen et al. discloses an instrument and method for applying and forming staples into body tissue to suture a hernial opening. The staple is applied to two pieces of body tissue on opposite sides of the opening which are gripped, approximated and held together by a tissue positioning assembly. U.S. Pat. No. 4,919,152 to Ger relates to a surgical instrument for placing a single clip which is proposed for use in direct hernia repair for closing sacs having narrow neck openings.
Commonly assigned U.S. patent application Ser. No. 07/782,290, filed Oct. 18, 1991, discloses a novel apparatus adapted to endoscopically apply staples for attaching objects such as surgical mesh in a manner which positively secures the object to body tissue without danger of separation thereof after the attachment is completed. This apparatus has proven to be highly effective in performing endoscopic surgical procedures, particularly, hernia repair.
The present invention is related to a novel endoscopic stapler incorporating a low pressure pneumatic system to provide the necessary forces to perform the stapling function. In accordance with the preferred embodiment of the present invention, the apparatus incorporates an initial or a staple-prepositioning function to facilitate proper placement of the staple relative to surgical mesh and body tissue prior to completion of the staple firing stroke.